Likelihood Surfaces for the Origin of the Allele

<div><p>(A) Assuming selection intensity is uniform spatially (i.e., <i>G_NS</i> = <i>G_EW</i><b>=</b> 0).</p> <p>(B) Allowing for north–south and east–west spatial gradients in selection (i.e., <i>G_NS</i> and <i>G_EW</i> are free parameters).</p> <p>Likelihoods were calculated at each of the black points and the surface was obtained by interpolation.</p>